package demo;

public class F1 extends F2 {
    public static void main( String[ ] args) {
        new F1( );
    }
    public F1( ){
        System.out.println( "4.执行F1的任务");}
}

class F2 extends F3 {
    public F2( ){
        this("2.调用F2的重载构造方法");//调用自己类的有参构造方法
        System.out.println( "3.执行F2的任务");}
    public F2( String s) {
        System. out. println( s);}
}

class F3{
    public F3( ){
        System. out.println( "1.执行E3的任务");}
}
